scholarly journals Effects of Successive Peak Flow Events on Hyporheic Exchange and Residence Times

2020 ◽  
Vol 56 (8) ◽  
Author(s):  
Tanu Singh ◽  
Jesus D. Gomez‐Velez ◽  
Liwen Wu ◽  
Anders Wörman ◽  
David M. Hannah ◽  
...  
Keyword(s):  
Peak Flow ◽  
Hyporheic Exchange ◽  
Residence Times

scholarly journals Dynamic Hyporheic Zones: Exploring the Role of Peak Flow Events on Bedform‐Induced Hyporheic Exchange

2019 ◽  
Vol 55 (1) ◽  
pp. 218-235 ◽  
Author(s):  
Tanu Singh ◽  
Liwen Wu ◽  
Jesus D. Gomez‐Velez ◽  
Jörg Lewandowski ◽  
David M. Hannah ◽  
...  
Keyword(s):  
Peak Flow ◽  
Hyporheic Exchange ◽  
Hyporheic Zones

Effect of sediment-organism interactions on hyporheic exchange in streams: role of sediment reworking time

2021 ◽  
Author(s):  
Shivansh Shrivastava ◽  
Michael Stewardson ◽  
Meenakshi Arora
Keyword(s):  
Flow Regime ◽  
Experimental Work ◽  
Laboratory Experiments ◽  
Hyporheic Exchange ◽  
Residence Times ◽  
Sediment Reworking ◽  
Hyporheic Flow ◽  
Mean Residence Times ◽  
Organism Interactions

<p>In-stream faunal organisms constantly interact with their habitat to modify its physical and hydraulic properties. However, little is known about how sediment-organism interactions could modify the hyporheic exchange. Previous experimental work investigating the effects of the activities of faunal organisms on exchange across the sediment-water interface has been largely conducted in small mesocosms or infiltration columns that do not represent the lotic environment adequately. Therefore, the experimental findings from these studies may not be transferable to flowing water environments (e.g., streams). Our previous experimental work demonstrated that sediment reworking by macroinvertebrates could significantly alter the hyporheic flux, mean residence times, and depth of exchange in streambeds. In this work, we explore how sediment-organism contact time influence the effect of the activities of model organisms, Lumbriculus variegatus, on the hyporheic flow regime. We conduct laboratory experiments in re-circulating flumes subject to different sediment reworking times (5 and 10 days). The hyporheic flow characteristics in these flumes were studied by conducting dye tracer tests after the bed sediments were reworked. Deposition of fecal pellets and holes/burrows dug by sample organisms were visible at the bed surface in both the experimental flumes. The flume reworked for a longer time exhibited higher hyporheic flux, longer median/mean residence times, and deeper depth of solute penetration compared to the flume reworked for a shorter period. The modification of hyporheic flow regime to different degrees depending on the sediment reworking times has direct relevance to the biogeochemistry in hyporheic zones, and thus on the overall quality of surface and sub-surface waters. We advocate that more intensive laboratory experiments and field investigations must be conducted to support the findings from our study and advance our understanding of the role of the activities of faunal organisms on fluvial ecosystem functioning.</p>

scholarly journals Flow and Residence Times of Dynamic River Bank Storage and Sinuosity-Driven Hyporheic Exchange

2017 ◽  
Vol 53 (10) ◽  
pp. 8572-8595 ◽  
Author(s):  
J. D. Gomez-Velez ◽  
J. L. Wilson ◽  
M. B. Cardenas ◽  
J. W. Harvey
Keyword(s):  
Hyporheic Exchange ◽  
Residence Times ◽  
River Bank

scholarly journals Analytical representations of the Residence Time Distribution (RTD) associated with Hyporheic Exchange beneath Dune-like bedforms at different sediment bed depths

2021 ◽  
Author(s):  
Ahmed Monofy ◽  
Fulvio Boano ◽  
Stanley Grant
Keyword(s):  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Hyporheic Zone ◽  
Hyporheic Exchange ◽  
Residence Times ◽  
Damkohler Number ◽  
Sediment Depth ◽  
Depth Effect ◽  
Damköhler Number

The hyporheic exchange below dune-shaped bedforms has a great impact on the stream environment. One of the most important properties of the hyporheic zone is the residence time distribution (RTD) of flow paths in the sediment domain. Here we evaluate the influence of an impervious layer, at a dimensionless sediment depth of db*=2πdbλ where λ is the dune wavelength, on the form of the hyporheic exchange RTD. Empirical RTDs were generated, over a range of db*values, from numerical particle tracking experiments in which 10000 particles sinusoidally distributed over a flatbed domain were released. These empirical RTDs are best represented by the Gamma, Log-Normal and Fréchet distributions over normalized bed depth of 0<=db*≤1.2,1.2<db*≤3.1, and db*>3.1, respectively. The depth dependence of the analytical distribution parameters is also presented, together with a set of regression formulae to predict these parameters based on db*with a high degree of accuracy (R2>99.8%). These results contribute to our understanding of the physical and mixing processes underpinning hyporheic exchange in streams and allow for a quick evaluation of its likely impact on nutrient and contaminant processing (e.g., based on the magnitude of the Damköhler number). Keywords: Dunes, bedforms, residence times distribution, sediment depth effect, Hyporheic residence times, analytical representation, two parametric distributions, Damköhler Number.

Dosimetry with 188Re-labelled monoclonal anti-CD66 antibodies

2006 ◽  
Vol 45 (03) ◽  
pp. 134-138 ◽  
Author(s):  
T. Kull ◽  
N. M. Blumstein ◽  
D. Bunjes ◽  
B. Neumaier ◽  
A. K. Buck ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Bone Marrow ◽  
Gamma Camera ◽  
Absorbed Dose ◽  
Correlation Coefficients ◽  
Residence Times ◽  
Reliable Prediction ◽  
Red Bone Marrow ◽  
Antibody Preparation ◽  
Simplified Method

SummaryAim: For the therapeutic application of radiopharmaceuticals the activity is determined on an individual basis. Here we investigated the accuracy for a simplified assessment of the residence times for a 188Re-labelled anti-CD66 monoclonal antibody. Patients, methods: For 49 patients with high risk leukaemia (24 men, 25 women, age: 44 ± 12 years) the residence times were determined for the injected 188Re-labelled anti-CD66 antibodies (1.3 ± 0.4 GBq, 5–7 GBq/mg protein, >95% 188Re bound to the antibody) based on 5 measurements (1.5, 3, 20, 26, and 44 h p.i.) using planar conjugate view gamma camera images (complete method). In a simplified method the residence times were calculated based on a single measurement 3 h p.i. Results: The residence times for kidneys, liver, red bone marrow, spleen and remainder of body for the complete method were 0.4 ± 0.2 h, 1.9 ± 0.8 h, 7.8 ± 2.1 h, 0.6 ± 0.3 h and 8.6 ± 2.1 h, respectively. For all organs a linear correlation exists between the residence times of the complete method and the simplified method with the slopes (correlation coefficients R > 0.89) of 0.89, 0.99, 1.23, 1.13 and 1.09 for kidneys, liver, red bone marrow, spleen and remainder of body, respectively. Conclusion: The proposed approach allows reliable prediction of biokinetics of 188Re-labelled anti-CD66 monoclonal antibody biodistribution with a single study. Efficient pretherapeutic estimation of organ absorbed dose may be possible, provided that a more stable anti-CD66 antibody preparation is available.

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